It is necessary, in counting mechanisms, to maintain the positioning torque which acts on the counting wheel at a certain value underneath which one cannot go, otherwise the viability of the operation of the mechanism will not be ensured, the counting wheel having the risk of no more advancing but of oscillating on itself, in a go and back movement.
The counting mechanisms of the above mentioned type, in which the positioning torque is obtained by a magnet, do not show adjusting means of the force exerted on the counting wheel by this magnet so that it is not possible to adjust this force to a value just higher than the minimum value ensuring a good operation, so that it is necessary to maintain a margin of security which has for effect a less of energy. As a matter of fact, at each pulse, the motor, most generally a balance wheel, is obliged to furnish a torque higher than the mere antagonist torque due to the resistance to the rotation of the time indicators.
The object of the present invention is to furnish an adjusting means of the positioning force exerted on the counting wheel by the positioning magnet, thus permitting to maintain this force at a minimum and, consequently, also to reduce to a minimum the supplement of energy which has to be furnished by the motor for overcoming this force.
To this effect, the counting mechanism according to the invention is characterized by the fact that the positioning magnet acting on the counting wheel is carried by a resilient blade submitted to the action of an adjusting screw against which it is elastically bearing. Rotation of this screw, in one direction or in the other, permits the magnet to move in one direction or in the other one and brings it closer to, or farther from, the plane of the counting wheel with which it cooperates, so as to permit the force it exerts on the said wheel to vary.